I was incorrect about Tokyo being small, but it is quite densely populated (>15k people/sq.mi. at 893 miles in sq area, hence a good candidate for pub trans) and in most examples of pub trans, the bigger its coverage area, the more expensive it becomes to maintain (and to use for its customers).

Also, the “problem” of sprawling cities isn’t a problem for everyone. There’s no way in hell that I’ll move back to a cramped rat race of a city like NYC, and I am sure I’m not alone in feeling this way.